Multi-layered hydrogenated p-type microcrystalline silicon windows for a-Si:H thin film solar cells on opaque substrates

Lee, Y.J.,Lee, S.H.,Schropp, R.E.I.,Lee, K.S.,Lim, J.W.,Yun, S.J. Pergamon Press 2016 International journal of hydrogen energy Vol.41 No.15

<P>The effects of multi-layered p-type microcrystalline (mu c-) Si:H windows on the performance of substrate-type amorphous Si:H thin film solar cells on opaque substrates were investigated. The results were well explained in terms of H-2-plasma-induced damage (HPID) at the p/i-interface and the near-interface region of the light-absorbing layer. The mu c-Si:H was deposited using plasma enhanced chemical vapor deposition in a H-2-rich atmosphere. A high microcrystalline volume fraction was obtained with a high H-2 dilution ratio, which can cause considerable HPID. Cell efficiency was enhanced with a multi-layered p-type mu c-Si:H composed of films with low and high crystalline volume fraction, compared to cells with single-layered mu c-Si:H. In the multi-layered p-type mu c-Si:H, the low crystalline film was placed on an i-Si:H layer to reduce HPID. The present work demonstrated that HPID was reduced at the p/i-interface and the near-interface region of the light-absorbing layer, and that the quality of the p-type mu c-Si:H needs to be a significant consideration to achieve high efficiency. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.</P>

H-Bridge 멀티-레벨 인버터 시스템

윤홍민(H.M.Yun),전재현(J.H.Jeon),이정표(J.P.Lee),장동제(D.J.Jang),나승호(S.H.Na),권봉현(B.H.Kwon) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-

본 논문은 대용량 전력변환장치인 멀티-레벨 인버터 시스템에서 출력 전압가변이 손쉬운 HBML (H-Bridge Multi-Level) 인버터의 Master와 Cell 제어기 구성에 관한 것이다. HBML 인버터는 각각의 단위 Cell을 저압에서 사용하는 인버터로 구성하며, 구조적으로 풀-브릿지(Full-Bridge) 인버터를 캐스케이드 방식으로 연결하여 고압출력을 얻을 수 있는 토폴로지이다. 시스템에서 Master와 Cell의 제어 처리를 한곳에 집중하지 않는 분산 제어 방식을 적용하여 통신 Data를 최적화하도록 구성하고, 이를 바탕으로 두 제어기를 고성능 원-칩(One-Chip) DSP로만 설계하였다. 모든 외부 모듈을 내장한 CPU로 제어기가 구성될 경우, 외부 노이즈에 강하며, 추가되는 하드웨어 결선을 최소화할 수 있다. 본 논문에서는 HBML 인버터 출력 생성 시 반드시 요구되는 출력 PWM 동기 및 위상전이(Phase Shift)를 각 제어기 자체에 내장된 모듈만을 이용해서 구현하였다.

Electrochemical performance of H₂O-CO₂ coelectrolysis with a tubular solid oxide coelectrolysis (SOC) cell

Lee, S.H.,Lee, J.W.,Lee, S.B.,Park, S.J.,Song, R.H.,Yun, U.J.,Lim, T.H. Pergamon Press ; Elsevier Science Ltd 2016 International journal of hydrogen energy Vol.41 No.18

<P>The H2O-CO2 electrochemical conversion process in solid oxide coelectrolysis (SOC) cells is potentially an efficient way to reduce CO2 emissions and to store renewable power simultaneously. In this study, a tubular solid oxide coelectrolysis (SOC) cell based on a general electrode support solid oxide fuel cell was fabricated and investigated. We fabricated tubular electrode support tubes through an extrusion process, and the essential SOC cell components, i.e., the electrolyte and the electrode, were then coated onto the surface of a ceramic support consecutively using a vacuum slurry and dip-coating method. The cell was operated while varying the operating temperature, cathode gas flow rate, and the supplied amount of H2O. The results demonstrate that the fabricated tubular SOC cell is a promising candidate for many practical applications, such as technology to mitigate climate change and power fluctuations associated with renewable energy. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.</P>

H-bridge 멀티-레벨 인버터의 파워Cell AVR에 관한 알고리즘

전재현(J.H.Jeon),윤홍민(H.M.Yun),김민극(M.K.KIM),이정표(J.P.Lee),장동제(D.J.Jang),나승호(S.H.Na),권봉현(B.H.Kwon) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-

본 논문은 멀티-레벨 H-bridge 인버터에서 입력전압 변동에 따른 AVR(Auto Voltage Regulation) 기능을 적용 그 타당성을 제안하였다. 기존의 범용 인버터에서 (V/F)로 구동되는 전동기 시스템에 있어서 인버터에 공급되는 입력 전압은 출력 주파수에 따라 출력 전압 비율을 일정하게 하고 기동에 필요한 전압을 더하여 출력하는 방식이다. 집중 제어 방식의 멀티-레벨 H-bridge 인버터에서는 Cell의 DC-Link 전압을 Master에서 받아들여서 각각의 Cell에 기준 전압값을 지령하게 된다. 그러므로 입력 전압 변동에 따른 DC-Link 전압의 변동이 발생하게 되면 상전압 Unbalance 가 발생하게 되어 부하가 원하는 출력 전압을 낼 수가 없게 된다. 또한 각각의 Cell을 제어하는 Master 제어기가 가지고 있는 문제점을 보완하여 각각의 Cell 제어기 스스로가 AVR을 수행하는 좀더 나은 방법을 제안하였다.

광음향효과를 이용한 MnSO₄ㆍ4H₂O,MnC₂ㆍ4H₂O,CuSO₄ㆍ5H₂O,Al₂O₃ : Cr의 전자상자성 공명 검출 Cr Crystals

윤수인,김학수,최규만,정중현 부산대학교 물성연구소 1985 물성연구소연구논문집 Vol.4 No.-

광음향효과를 이용하여 MnSO₄ㆍ4H₂O, MnCl₂ㆍ4H₂O, CuSO₄ㆍ5H₂O 및 Al₂O₃ : Cr 결정의 상자성 공명을 검출했다. X-밴드 마이크로파의 도파관 내에 광음향 cell을 장치하고 관내에 넣은 short의 위치를 조절하여 도파관 자체가 공명공동이 되도록 함으로써 장치의 감도를 개선했다. g값과 공명신호의 자기장반가폭으로 MnSO₄ㆍ4H₂O의 Mn²^(+)로 부터 1.99±0.03과 260 gauss를, CuSO₄ 5H₂O의 Cu²^(+)로부터 2.31±0.02와 200 gauss를, MnCl₂ 4H₂O로부터 2.06±0.04와 690 gauss를 그리고 Al₂O₃:Cr의 Cr³^(+)로부터 1.97±0.03과 480 gauss를 얻었다. The electron paramagnetic resonances were observed at room temperature in concentrated system, MnSO₄ㆍ4H₂O, MnCl₂ㆍ4H₂O and CuSO₄ㆍ5H₂O and in the dilute system, Al₂O₃: Cr, using photoacoustic technique. A commercial x-band microwave system was modified by introducing the photoacoustic (PA) cell into the microwave cavity to improve the sensitivity of the PA system. The observed g-values and half-widths were 1.99±0.03 and 260 gauss for Mn²^(+) in MnSO₄ㆍ4H₂O crystal, 2.31±0.02 and 200 gauss for Cu²^(+) in CuSO₄ 5H₂O crystal, 2.06±0.04 and 690 gauss for MnCl2 4H₂O crystal, and 1.97±0.03 and 480 gauss for CrCr³^(+) in Al₂O₃:Cr crystal, respectively.

등가응력구배 시편에 대한 J-Q 해석

윤정한(J. H. Yun),석창성(C. S. Seok),구재민(J. M. Koo),이정민(J. M. Lee),박건태(K. T. Park) 한국정밀공학회 2014 한국정밀공학회 학술발표대회 논문집 Vol.2014 No.5월

The regulation of TIM-3 transcription in T cells involves c-Jun binding but not CpG methylation at the TIM-3 promoter

Yun, S.J.,Jun, K.J.,Komori, K.,Lee, M.J.,Kwon, M.H.,Chwae, Y.J.,Kim, K.,Shin, H.J.,Park, S. Pergamon Press 2016 Molecular immunology Vol.75 No.-

<P>Tim-3 is an immunomodulatory protein that is expressed constitutively on monocytes but is induced in activated T cells. The mechanisms involved in the regulation of TIM-3 transcription are poorly understood. In the present study, we investigated whether methylation of the TIM-3 promoter is involved in regulating TIM-3 transcription in T cells, and identified a transcription factor that regulates TIM-3 transcription by associating with the TIM-3 minimal promoter region. Pyrosequencing of the TIM-3 promoter up to 1440 bp revealed 11 hypermethylated CpG sites and 4 hypomethylated CpG sites in human CD4(+) T cells as well as in CD11b(+) cells. Dimethylation of histone H3 lysine 4 (H3K4), a mark of transcriptional activation, was predominantly found in the proximal TIM-3 promoter 954 to 34 by region, whereas trimethylation of H3K9 and H3K27, which are markers of transcriptional suppression, were mostly observed in the distal promoter -1549 to -1048 bp region in human CD4+ T cells and CD11b(+) cells. However, no change in the methylation status of CpG sites and the histone H3 in the TIM-3 promoter was found during induction of TIM-3 transcription in T cells. Finally, AP-1 involvement in TIM-3 transcription was shown in relation with the TIM-3 minimal promoter 146 to +144 by region. The present study defines the minimal TIM-3 promoter region and demonstrates its interaction with c-Jun during TIM-3 transcription in CD4(+) T cells. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Induction of bone formation by <i>Escherichia coli</i>‐expressed recombinant human bone morphogenetic protein‐2 using block‐type macroporous biphasic calcium phosphate in orthotopic and ectopic rat models

Park, J‐,C.,So, S‐,S.,Jung, I‐,H.,Yun, J‐,H.,Choi, S‐,H.,Cho, K‐,S.,Kim, C‐,S. Blackwell Publishing Ltd 2011 Journal of periodontal research Vol.46 No.6

<P><I>Park J‐C, So S‐S, Jung I‐H, Yun J‐H, Choi S‐H, Cho K‐S, Kim C‐S. Induction of bone formation by</I> Escherichia coli<I>‐expressed recombinant human bone morphogenetic protein‐2 using block‐type macroporous biphasic calcium phosphate in orthotopic and ectopic rat models. J Periodont Res 2011; 46: 682–690. © 2011 John Wiley & Sons A/S</I></P><P><B>Background and Objective: </B> The potential of the <I>Escherichia coli</I>‐expressed recombinant human bone morphogenetic protein‐2 (ErhBMP‐2) to support new bone formation/maturation using a block‐type of macroporous biphasic calcium phosphate (bMBCP) carrier was evaluated in an orthotopic and ectopic rat model.</P><P><B>Material and Methods: </B> Critical‐size (Φ 8 mm) calvarial defects and subcutaneous pockets in 32 Sprague–Dawley rats received implants of rhBMP‐2 (2.5 μg) in a bMBCP carrier or bMBCP alone (control). Implant sites were evaluated using histological and histometric analysis following 2‐ and 8‐wk healing intervals (eight animals/group/interval).</P><P><B>Results: </B> ErhBMP‐2/bMBCP supported significantly greater bone formation at 2 and 8 wk (10.8% and 25.4%, respectively) than the control at 2 and 8 wk (5.3% and 14.0%, respectively) in calvarial defects (<I>p</I> < 0.01). Bone formation was only observed for the ErhBMP‐2/bMBCP ectopic sites and was significantly greater at 8 wk (7.5%) than at 2 wk (4.5%) (<I>p</I> < 0.01). Appositional and endochondral bone formation was usually associated with a significant increase in fatty marrow at 8 wk. The bMBCP carrier showed no evidence of bioresorption.</P><P><B>Conclusion: </B> ErhBMP‐2/bMBCP induced significant bone formation in both calvarial and ectopic sites. Further study appears to be required to evaluate the relevance of the bMBCP carrier.</P>

Effects of Lewis number and preferential diffusion on flame characteristics in 80%H₂/20%CO syngas counterflow diffusion flames diluted with He and Ar

Park, J.,Lee, D.H.,Yoon, S.H.,Vu, T.M.,Yun, J.H.,Keel, S.I. Pergamon Press ; Elsevier Science Ltd 2009 International journal of hydrogen energy Vol.34 No.3

Numerical study is conducted to grasp flame characteristics in H<SUB>2</SUB>/CO syngas counterflow diffusion flames diluted with He and Ar. An effective fuel Lewis number, applicable to premixed burning regime and even to moderately stretched diffusion flames, is suggested through the comparison among fuel Lewis number, effective Lewis number, and effective fuel Lewis number. Flame characteristics with and without the suppression of the diffusivities of H, H<SUB>2</SUB>, and He are compared in order to clarify the important role of preferential diffusion effects through them. It is found that the scarcity of H and He in reaction zone increases flame temperature whereas that of H<SUB>2</SUB> deteriorates flame temperature. Impact of preferential diffusion of H, H<SUB>2</SUB>, and He in flame characteristics is also addressed to reaction pathways for the purpose of displaying chemical effects.

A study on flame structure and extinction in downstream interaction between lean premixed CH₄-air and (50% H₂+50% CO) syngas-air flames

Kim, J.S.,Park, J.,Kwon, O.B.,Bae, D.S.,Yun, J.H.,Keel, S.I. Pergamon Press ; Elsevier Science Ltd 2011 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.36 No.9

Downstream interactions between lean premixed flames with mutually different fuels of (50% H<SUB>2</SUB>+50% CO) and CH<SUB>4</SUB> are numerically investigated particularly on and near lean extinction limits in order to provide fundamental database for the design of cofiring burners with hydrocarbon and syngas under a retrofit concept. In the current study the anomalous combination of lean premixed flames is provided such that even a weaker CH<SUB>4</SUB>-air flame temperature is higher than a stronger syngas-air flame temperature, and, based on a deficient reactant concept, the effective Lewis numbers Le<SUB>eff</SUB>∼1 for lean premixed (50% H<SUB>2</SUB>+50% CO)-air mixture and Le<SUB>D</SUB><1 for CH<SUB>4</SUB>-air mixture. It is found that the interaction characteristics between lean premixed (50% H<SUB>2</SUB>+50% CO)-air and CH<SUB>4</SUB>-air flames are quite different from those between the same hydrocarbon flames. The lean extinction boundaries are of slanted shape, thereby indicating strong interactions. The upper extinction boundaries have negative flame speeds while the lower extinction boundaries have both negative and positive flame speeds. The results also show that the flame interaction characteristics do not follow the general tendency of Lewis number, which has been well described in interactions between the same hydrocarbon flames, but have the strong dependency of direct interaction factors such as flame temperature, the distance between two flames, and radical-sharing. Importance of chain carrier radicals such as H is also addressed in the downstream interactions between lean premixed (50% H<SUB>2</SUB>+50% CO)-air and CH<SUB>4</SUB>-air flames.